This invention relates to a silicon controlled rectifier (SCR) bridge inverter, and more particularly to a circuit topology which requires only a single gate turn-off (GTO) thyristor to commutate all SCR switches in a polyphase bridge inverter.
Commutator circuits for polyphase SCR bridge inverters are generally complex, because of the need to provide separate commutation for each switching pole. The recent development of gate turn-off (GTO) thyristors with high current and voltage ratings (up to 800 A, 2500 volts, with even higher ratings possible) has made feasible a polyphase SCR bridge inverter suitable for power levels above 1 kW using one and only one GTO thyristor to commutate all SCR switches. Absence of conventional commutation circuitry reduces cost, size, weight and power losses compared to the present state of the art. That is important for extensive commercial applications of a polyphase SCR bridge inverter, such as in converting solar dc power into ac power.